The standard RAM test will only test out the standard amount of RAMon teh machine: it does not look to see if there is more.

Also, the standard V2 kernel/player app will only enable the standard amount of RAM after boot. You should get hold of 2.1 which will enable the new stuff.

You should install HiJack (about 400-odd) and get to the HiJack menu. Have a look at the Vital Signs entry and it will tell you how much it finds.